A study of sodium silicate in aqueous solution and sorbed by synthetic magnetite using in situ ATR-FTIR spectroscopy.
A study of sodium silicate in aqueous solution and sorbed by synthetic magnetite using in situ ATR-FTIR spectroscopy.
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DOI：
10.1016/j.jcis.2008.08.061
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发表时间：
2008-12
影响因子：
9.9
通讯作者：
Xiaofang Yang;Payman Roonasi;A. Holmgren
中科院分区：
文献类型：
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作者：
Xiaofang Yang;Payman Roonasi;A. Holmgren
用原位衰减全反射傅里叶变换红外光谱研究了不同pH值(pH 7~11)和不同初始硅酸盐浓度(1×10−3和10×10−3molL−1)条件下合成磁铁矿(Fe3O4)对水玻璃的吸附。水玻璃溶液和吸附在纳米磁铁矿上的红外光谱分析清楚地表明，不同的硅酸盐物种随pH和二氧化硅浓度的变化而变化。红外光谱表明，所研究的硅酸盐浓度(10×10−3molL−1)在低pH时含有聚合或缩合的硅酸盐物种，在高pH时含有单体。单体的缩合导致光谱区域的高频部分(>；1050 cm−1)的吸收强度增加，该区域包含有关溶液中的硅酸盐和吸附的硅酸盐的信息。在研究的pH范围内，吸附硅酸盐和解吸过程中的吸附硅酸盐的红外光谱均表明磁铁矿表面存在不同类型的表面络合物。吸附机理符合配体交换反应，在低表面负载量条件下，单齿和双齿络合物均可存在，络合物的相对比例与溶液的pH值和浓度有关。表面负载量较高时，磁铁矿表面发生齐聚反应。
The sorption of sodium silicate by synthetic magnetite (Fe3O4) at different pH conditions (pH 7–11) and initial silicate concentrations (1×10−3and 10×10−3molL−1) was studied using in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. The analysis of infrared spectra of sodium silicate in solution as well as adsorbed on magnetite nano-particles clearly showed the evolution of different silicate species depending on pH and silica concentration. The silicate concentration studied (10×10−3molL−1) contained polymeric or condensed silicate species at lower pH as well as monomers at high pH, as evident from infrared spectra. Condensation of monomers resulted in an increased intensity of absorptions in the high frequency part (>1050 cm−1) of the spectral region, which contains information about both silicate in solution and sorbed silicate viz. 1300 cm−1–850 cm−1. In the pH range studied, infrared spectra of sorbed silicate and sorbed silicate during desorption both indicated the presence of different types of surface complexes at the magnetite surface. The sorption mechanism proposed is in accordance with a ligand exchange reaction where both monodentate and bidentate complexes could exist at low surface loading level, the relative proportion of the complexes being due to both pH and concentration in solution. Oligomerization occurred on the magnetite surface at higher surface loading.